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1
FUNDAMENTOS DEL CONTROLADOR PROGRAMABLE
2
¿QUE ES UN CONTROLADOR
PROGRAMABLE?
PROGRAMMABLECONTROLLER
ENTRADAS
• A solid state device that controls output devices based on the status of the inputs, and a user developed program.
• Originally developed to directly replace relays used for discrete control.
OUTPUTS
CR
3
INPUT DEVICES
• Pushbuttons
• Selector Switches
• Limit Switches
• Level Switches
• Photoelectric Sensors
• Proximity Sensors
• Motor Starter Contacts
• Relay Contacts
• Thumbwheel Switches
• 120 VAC
• 240 VAC
• 12 VDC
• 24 VAC/VDC
• TTL
4
OUTPUT DEVICES
• Valves
• Motor Starters
• Solenoids
• Control Relays
• Alarms
• Lights
• Fans
• Horns
Relays
• 120 VAC/VDC
• 240 VAC/VDC
• 24 VAC/VDC
Triac
• 120 VAC
MOSFET
• 24 VDC
5
CR
Isolation
BarrierIsolation
Barrier
Inside a PLC
CentralProcessor
MEMORY
program data
HighVoltage
HighVoltage
Low Voltage
AC Power Supply85-264 VAC, 50/60Hz
Circuits
DC Power Supplyor
Communications
Input
Circuits
Output
6
PLC’s Come in a Variety of Sizes...
Micro– Typically less than 32 I/O
Small– Typically less than 128 I/O
Medium– Typically less than 1024 I/O
Large– Typically greater than 1024 I/O
7
And a variety of shapes/configurations
Packaged
Packaged with expansion
Modular (rack less)
Modular (rack based)
Distributed
8
Packaged PLC
INPUTSStop
Start
I/Ø I/1
Motor
M1 OUTPUTO/3
Power supply, Inputs, Outputs and Communication port are enclosed in a single package.INPUT and OUTPUT devices are wired individually to the packaged controller.
OOOOOOOOOOOO
9
Packaged PLC with Expansion
Base is identical to the standard Packaged PLC, but it also has the ability to drive additional I/O.The most common form of expansion is a block of I/O that uses the same base, or makes use of different types of expansion “modules”.Connections between the base and the expansion device is either direct (mating connector), or by using a wired approach (ribbon connector is very common).
OOOOOOOOOOOO
2 Slot ExpansionChassis
10
Modular PLC’s(The Ultimate in Flexibility)
OUT 0
IN 0
PROG
SLC 5/03 CPURUN
FLT
BATT
FORCE
RS232
DH485
RUN REM
DH-485 Port status indicator
RS-232 Port status indicator
Processor RUN indicatorProcessor FLT indicator
Battery status indicator
Force I/O indicator
Keyswitch RUN, REM, PROG
DH-485 Port connection for programming terminal
RS-232 Port for programming terminal
Power Supply
Input Modules
Output Modules
Mix N Match Components– Processors, Power Supplies and I/O are plugged into a rack or chassis– Available in Small, Medium, and Large platforms– Flexibility results in higher costs when compared to packaged
Modular PLC’s are either rack based or are rack-less
Allen-Bradley SLC-500 and PLC 5 are modular PLC’s
11
Modular Rack-Less PLC’s(The Ultimate in Flexibility)
Identical in functionality to rack based PLC’s
Typically not as robust (packaging)
Typically found on “smaller” (small and medium) sized PLC’s.
Will likely become the prevalent form of packaging in the future.
12
Distributed
Rely on communications for EVERYTHING
All I/O is connected to the processor through a “High Speed” data link.
Typically found on “larger” (medium and large) PLC’s.
For certain applications this type of form factor is very advantageous.
Usually higher cost for hardware, but much lower cost for system integration.
13
Typical PLC Application
Motor
Solenoid 1 Solenoid 2
Solenoid 3
Sensor 1
Sensor 2
Ingredient A Ingredient B
14
Operation of Mixer(Defining the Outputs)
Solenoid 1On = Sol 3 is off, and Motor is off, and Sensor 2 is off,
and Auto Switch is onOff = Sol 3 is on, or Motor is on, or Sensor 2 is on
Solenoid 2On = Sol 3 is off, and Motor is off, and Sensor 2 is onOff = Sol 3 is on, or Motor is on, or Sensor 1 is on
MotorOn = Sensor 1 is on, and Solenoid 2 is off, and
Solenoid 1 is offOff = Solenoid 3 on
Solenoid 3On = Sol 1 is off, and Sol 2 is off, and Motor has run
for 30 sec.Off = Solenoid 3 has been on for 60 sec.
Motor
Solenoid 1 Solenoid 2
Solenoid 3
Sensor 1
Sensor 2
Ingredient A
Ingredient B
15
Input Wiring
Terminal Block
1
2
3
4
5
6
7
8
9
Input Devices
L1
L1
L210
COM
PLC
Isolation
Barrier
16
Output Wiring
OUT 1
Output Devices
L2
L2
L1OUT 1
OUT 2
OUT 2
OUT 3
OUT 3
OUT 4
OUT 4
OUT 5
OUT 5
OUT 6
OUT 6
CR
L1PLC
Terminal Block
Isolation
Barrier
17
PLC Operating Cycle
Input Scan
Program Scan
Output Scan
Housekeeping
START
Communications
18
Ladder Logic Concepts
| | |/| ( )
Read / ConditionalInstructions
Write / ControlInstruction
| | |/| ( )
| | |/| ( )
| |
| | |/| ( )
| | ( )
| |
Start (Rung #1)
End (Rung #5)
19
Ladder Logic Concepts
Input Instructions Output Instruction
| | |/| ( )
Logical ContinuityT T T
| | |/| ( )
No Logical ContinuityT F F
20
Logical AND Construction
| |I/4
| |I/5
( )O/0
IF input 004 AND input 005 have power
THEN energize output 0
Off
21
Logical AND Construction
IF input 4 AND input 5 have power
THEN energize output 0
| |I/4
| |I/5
( )O/0
Logical Continuity
T T T
On
22
Logical OR Construction
| |I/4
| |I/5
IF input 4 OR input 5 have power
THEN energize output 0
( )O/0 Off
23
Logical OR Construction
IF input 4 OR input 5 have power
THEN energize output 0
| |I/4
| |I/5
( )O/0
Logical Continuity
T
F
On
24
Logical OR Construction
IF input 4 OR input 5 have power
THEN energize output 0
| |I/4
| |I/5
( )O/0
Logical Continuity
T
F
On
| |I/4
| |I/5
( )O/0
Logical Continuity
F
T
Off
25
Complex Construction
|/|I/11
| |I/5
|/|I/7
|/|I/1
| |I/3
| |I/2
| |I/4
|/|I/0
| |I/1
| |I/1
|/|I/8
| |I/9
( )O/0
| |I/10
26
Input Instructions - XIC, XIO
False
The status of the instruction is If the data file bit is
Logic 0
Logic 1 False
True
True
XICExamine if Closed
-| |-
XIOExamine if Open
-|/|-
INPUT
Input Push Button
27
Output Instruction - OTE
RungState
StatusBit
OutputTerminal
De-energized
ENERGIZEDTRUE
FALSE
ON
OFF
OTEOutput Energize
-( )-
| | |/| ( )
T T T
OUTPUT
Output Pilot Light
28
Putting it all Together
| | ( )
OUT 0
IN 0
PROG
SLC 5/03 CPU
RUN
FLT
BATT
FORCE
RS232
DH485
RUN REM
INPUT OUTPUTINPUT
IN 0 OUT 0
29
Addressing Example
L1 L2PB1 LS1 FS2 SOL6
DEVICE
PB1
LS1
FS2
SOL6
| | ( )| | | |I:1/1 I:1/2 O:3/1I:1/3
ADDRESS
L1 L2
I:1/1
I:1/2
I:1/3
O:3/1
30
Relay Logic to Ladder Logic
INPUT Address Assignment:PB1- I:1/1 PB2- I:1/4LS1- I:1/2 LS2- I:1/3LS3- I:1/5 LS4- I:1/6
OUTPUT Address Assignment:SOL2- O:3/0 M1- O:3/1
I:1/1 I:1/2 O:3/0
|/|
CR3
CR3 M1
PB1 LS1 SOL2
PB2LS2
LS3
LS4O:3/1
| | | | ( )
I:1/4I:1/3
I:1/5
B3/0| | | | ( )
| |
|/|B3/0
( )| |I:1/6
31
SOURCING vs. SINKING
The Mystery...
32
DC Power Supply
+
-
DC COM
+VDC
SOURCING vs. SINKINGDC I/O (General)
33
DC Power Supply
DC Power Supply
+
- DC COM
+
-
+VDC
SOURCING Pushbutton SINKING Pushbutton
SOURCING vs. SINKINGDC I/O (General)
34
DC Power Supply
Field Device
DC Input Module
DC Input Module
Field Device
DC Power Supply
+
- DC COM
+
-
+VDC
IN1
IN1
SOURCING vs. SINKINGDC Inputs
35
DC Power Supply
DC Power Supply
Field Device
Field Device
DC Output Module
DC Output Module
+
+
-
-
DC COMDC COM
+VDC +VDC
OUT1
OUT1
SOURCING vs. SINKINGDC Outputs
36
RULES
Field devices on the positive side (+VDC) of the field power supply are sourcing field devices.
Field devices on the negative side (DC COM) of the field power supply are sinking field devices.
Sourcing field devices must be connected to sinking I/O cards and vice versa.
Sinking field devices must be connected to sourcing I/O cards and vice versa.
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